import java.util.PriorityQueue;

public class Text {
    public static void main1(String[] args) {
        PriorityQueue<student> priorityQueue=new PriorityQueue<>();
        priorityQueue.offer(new student(1));
        priorityQueue.offer(new student(15));
        System.out.println(priorityQueue.peek());
    }

    public static void main2(String[] args) {
        PriorityQueue<student> priorityQueue=new PriorityQueue<>();
        priorityQueue.offer(null);
    }
}
class student{
    int age;

    public student(int age) {
        this.age = age;
    }
}